Scarlet Frost Dragon:
Unhappy Girl with Riryoku Field. For the "Destroy 6 monsters" mission use a Ninja deck with Riryoku Field and ninja traps to dodge Tribute to the Doomed and Frost Dragon Effect (keep in mind that you'll lose some LP due to Reaver and Sunfish effects). For the fusion mission use Paladin, summon him as fast as you can
Scarlet Sacred Phoenix of Nephtys:
Red-Eyes Zombie deck (the pvp one with Gozuki, Insights and stuff) with Dimension Gate to counter Wild Tornado. Beatdown skill is also required to beat Phoenix attack
Scarlet Ninja:
Again the same PVP RE Zombie deck. The Ninja is by far the hardest to counter so let this be the last to be beaten. Add Wild Tornados to destroy the traps and Kuriboh to avoid Red Ninja. The effect damage challenges in the 30F is the hardest, all I could think was Grave Vassal so I exhausted his resources (2 Etaqua), brought 2 Union (in case of Kuriboh) and attacked praying...
... to God, SPhere Ebola wasn't in his hand and luckilly it worked. For the 7000 Battle damage: again use REZ, exhaust his etaquas and use Inspiration (2 or 3) in the last attack IN THE DAMAGE STEP (atesting that Ebola is still in his deck)